Slip mechanism for subterreanean wells

Abstract

A slip mechanism is provided to effect the anchoring of an inner tubular conduit to the inner wall of a larger surrounding tubular conduit such as the casing of the well. Two annular cam elements are disposed in axial alignment for slidable movements on the inner tube. Such cam elements have a plurality of peripherally spaced, axially extending, slots formed in their peripheries. A set of first slip members are radially slidably disposed in a portion of the axial slots and a set of second slip members are radially slidably disposed in the remainder of the axial slots. The slips are provided with an inclined cam surface which cooperates with a correspondingly shaped surface provided in the slot receiving that portion in the cam element. The slips have external teeth and may be of identical configuration, but are reversed when inserted into oppositely extending slots provided in separate cam elements. Axial movement of the two cam elements toward each other effect the concurrent radial outward displacement of both sets of slips and the simultaneous wedging engagement of all the slips with the casing wall. Each slip is wedged between one cam element and the casing and is attached to the other cam element preventing retraction of the cam elements and inadvertent dislodging of the slip mechanism due to extrusion of the packing elements and to pressure differentials existing in the annulus between the inner and outer conduit.